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Unit 3B:
Biological Bases of Behavior:
The Brain
Unit Overview
• The Tools of Discovery: Having Our Head
Examined
• Older Brain Structures
• The Cerebral Cortex
• Our Divided Brain
• Right-Left Differences in the
Intact Brain
• The Brain and Consciousness
.
The Tools of Discovery:
Having Our Head Examined
Introduction
• Lesion- in the interests of science
or medicine, scientists can
selectively destroy tiny clusters of
brain cells/tissue.
• Today, we can also stimulate
(electrically/chemically) various
parts of the brain and note the
effects.
Recording the Brain’s Electrical Activity
We are now able to detect
an electrical impulse from a
single neuron = detect
exactly where information
goes from any stimulus.
Electroencephalogram
(EEG) reads regular brain
waves of electrical activity
that sweeps the surface of
the brain = a computer can
filter out unrelated brain
activity
http://www.youtube.com/watch?v=bO_ZtIxcr0&feature=related&safe=active
Neuroimaging Techniques
• CT (Computed Tomography)
scan
– (CAT Scan)- Takes X-ray
photographs that can reveal
brain damage
–
http://www.youtube.com/watch?v=uHu9aa0QDiE&feature=related&safe=act
ive
• PET (Positron Emission
Tomography) scan
– Shows the brain’s
consumption of glucose
(sugar) which creates a visual
display of brain activity
•
http://www.youtube.com/watch?v=d9iOxMFmPlA&feature=related&safe=active
Neuroimaging Techniques
• MRI (Magnetic Resonance
Imaging)- brain scan where the
head is put in a strong magnetic
field which aligns, and then
disorients the atoms = pictures
of brain’s soft tissue
•
http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active
• fMRI (Functional MRI)- reveals brain’s
functioning and structure. Where the
brain is active, the blood goes.
– The brain “lights up” as you
perform different mental functions
–
http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active
Older Brain Structures
The Brainstem
• Brainstem
–Medulla
–Pons
–Reticular formation
The Thalamus
• Thalamus
–All the senses
EXCEPT smell
The Cerebellum
• Cerebellum
–“Little brain”
The Limbic System
• Limbic System
–Hippocampus
The Limbic System
The Amygdala
• Amygdala
–Aggression
and fear
The Limbic System
The Hypothalamus
• Hypothalamus
–Influence on the pituitary gland
–Reward Centers
–Reward deficiency
syndrome
The Cerebral Cortex
Introduction
• Cerebrum
– Cerebral cortex
• Fabric of interconnected neural
cells covering the cerebral
hemispheres
• The body’s ultimate control and
information-processing center
• Gives certain areas of the body
different attention -DEMO
• Moving up the ladder of life means a
larger cerebral cortex
– Allows humans to adapt, learn,
and think
Structure of the Cortex
• Glial cells (“glue cells”) – provide the
myelin and nutrients that neurons need.
– The more complex the animal, the
more glial cells
• Lobes
– Frontal lobes – speaking, muscle
movement, and making
plans/judgments
– Parietal lobes – receives sensory
information for touch and body position
– Occipital lobes – receives information
from visual fields
– Temporal lobes – receive information
from the opposite ear
• Scenario DEMO
Functions of the Cortex - Association Areas
• Association areasareas of the cortex
that are not involved
in primary motor or
sensory functions, but
are involved in higher
mental functioninglearning, speaking,
remembering, thinking
–
Phineas Gage Video
Functions of the Cortex Motor Functions
• Motor Cortex (in the frontal
lobe) output controls
voluntary movements
• Mapping the Motor Cortex –
different areas of the cortex
control different parts of your
body
– Being able to predict a monkey’s
movement .10 seconds before it
happens
• Neural Prosthetics- research
showing it is possible to
control objects by tracking
what neurons fire in the
motor cortex
Functions of the Cortex - Sensory Functions
• Sensory Cortex– Front of the
parietal lobes that
registers and
processes body
touch and
movement
sensations
– The more sensitive
the body region,
larger the sensory
cortex area
devoted to it.
Functions of the Cortex
Language
• Aphasia – an impaired use of language can result
from damage to one of the following areas– Broca’s area (disrupts speaking)– controls language
expression and directs the muscle movements
involved in speech
– Wernicke’s area (disrupts understanding) – controls
language reception – a brain area involved in
language comprehension and expression
Language Continued
• Is language only located in the left hemisphere?
– Left handed and divided brain woman• When a word is in her left visual field (processed in right half
of brain) she can write it but not say it
• When a word is in her right visual field (processed in left half
of brain) she can say it, but not write it
• Clear scientific evidence that in some people the capacities
for spoken and written language may be located in
different hemispheres
• Learning a second language
– At a young age- the brain shows activity in the same area as your
native language
– After childhood- brain activity is in an adjacent area while
speaking
Language
Language
Language
Language
Language
Language
•
The
Brain’s
Plasticity
Brain Damage
– Plasticity – the ability of the brain to modify
itself after some types of damage (VIDEO)
• The younger the child, the greater
chance the remaining hemisphere can
take over functions of the surgically
removed one
• Unused or damaged parts of the brain
looks for signals to process (Deaf people
have enhanced peripheral vision)
– Constraint-induced therapy – restrain a fully
functioning limb to force the “bad limb” to
be reprogramed
– Neurogenesis – neural stem cells to rebuild
or replace damaged brain cells
Our Divided Brain
Right v Left Brained
• The “right versus left brain” is a myth.
• There is no evidence to support the
idea that the two brains do not
communicate with one another.
• Neither “logic” or “musical ability” is
kept in one brain or the other.
• HOWEVER, there is NEW research that
suggests lateralization (hemispheric
specialization)- functions on the brain
may be either on the left or right
– The right hemisphere processes emotional
expressions. Which face is happier?
Splitting the Brain
• Vogel and Bogen
– Corpus-callosum – large band of
neural fibers (axons) that connect
the two brain hemispheres and
carry messages
– Split brain – a surgeon can cut
through the corpus callosum (to
eliminate seizures) (VIDEO)
– It is as if you have two competing
brains; and will follow their own
instructions- “two separate minds”
• Left- deliberating (rationalize)
• Right- simple requests
• Shirt unbutton/Grocery store
items
• “Walk”
Demos
-Two Brains
-Hand/Leg
-Hand tapping
-Circle/Square
The Brain and Consciousness
Introduction
• Consciousness – our
awareness of
ourselves and our
environment
– Reproductive advantage?
– Acting on long term interests
rather than short term
pain/pleasure?
– Survival of being able to read
other people?
Cognitive Neuroscience
• Cognitive neuroscience – study of
brain activity linked with cognition
– Perception, thinking, memory,
and language
– How do the mind and the brain
interact?
– Non-communicative woman
after car accident with no
signs of conscious awareness
was asked to imagine people
playing tennis
• Resulted in fMRI scan with
activity
The Two-Track Mind
• Two-Track Mind
– Visual perception track
• enables us to recognize things and to
plan actions
– Visual action track
• Guides our moment-to-moment actions
• Much of our everyday thinking, feeling, and
acting operates outside our conscious
awareness - - you may act before you are
conscious of doing something (driving familiar
route)
– Seeing a bird flying
• Cognitive- It’s a cardinal!
• Sub-processing- color, form, movement,
distance
The End
Definition
Slides
Lesion
= tissue destruction; a brain lesion is a
naturally or experimentally caused
destruction of brain tissue.
Electroencephalogram (EEG)
= an amplified recording of the waves of
electrical activity that sweep across the
brain’s surface. These waves are
measured by electrodes placed on the
scalp.
CT (computed tomography)
Scan
= a series of X-ray photographs taken from
different angles and combined by
computer into a composite representation
of a slice through the body.
• Also called CAT scan.
PET (positron emission
tomography) Scan
= a visual display of brain activity that
detects where a radioactive form of
glucose goes while the brain performs a
given task.
MRI (magnetic resonance
imaging)
= a technique that uses magnetic fields and
radio waves to produce computergenerated images of soft tissue. MRI
scans show brain anatomy.
fMRI (functional MRI)
= a technique for revealing bloodflow and,
therefore, brain activity by comparing
successive MRI scans. fMRI scans show
brain function.
Brainstem
= the oldest part of the central core of the
brain, beginning where the spinal cord
swells as it enters the skull; the brainstem
is responsible for automatic survival
functions.
Medulla
= the base of the brainstem; controls
heartbeat and breathing.
Reticular Formation
= a nerve network in the brainstem that
plays an important role in controlling
arousal.
Thalamus
= the brain’s sensory switchboard, located
on top of the brainstem; it directs
messages to the sensory receiving areas
in the cortex and transmits replies to the
cerebellum and medulla.
Cerebellum
= the “little brain” at the rear of the
brainstem; functions include processing
sensory input and coordinating movement
output and balance.
Limbic System
= doughnut-shaped neural system (including
the hippocampus, amygdala, and
hypothalamus) located below the cerebral
hemispheres; associated with emotions
and drives.
Amygdala
= two lima bean-sized neural clusters in the
limbic system; linked to emotion.
Hypothalamus
= a neural structure lying below (hypo) the
thalamus; it directs several maintenance
activities (eating, drinking, body
temperature), helps govern the endocrine
system via the pituitary gland, and is
linked to emotion and reward.
Cerebral Cortex
= the intricate fabric of interconnected neural
cells covering the cerebral hemispheres;
the body’s ultimate control and
information-processing center.
Glial Cells
= cells in the nervous system that support,
nourish, and protect neurons.
Frontal Lobes
= portion of the cerebral cortex lying just
behind the forehead; involved in speaking
and muscle movements and in making
plans and judgments.
Parietal Lobes
= portion of the cerebral cortex lying at the
top of the head and toward the rear;
receives sensory input for touch and body
position.
Occipital Lobes
= portion of the cerebral cortex lying at the
back of the head; includes areas that
receive information from the visual fields.
Temporal Lobes
= portion of the cerebral cortex lying roughly
above the ears; includes the auditory
areas, each receiving information primarily
from the opposite ear.
Motor Cortex
= an area at the rear of the frontal lobes that
controls voluntary movements.
Sensory Cortex
= area at the front of the parietal lobes that
registers and processes body touch and
movement sensations.
Association Areas
= areas of the cerebral cortex that are not
involved in primary motor or sensory
functions; rather, they are involved in
higher mental functions such as learning,
remembering, thinking, and speaking.
Aphasia
= impairment of language, usually caused by
left hemisphere damage either to Broca’s
area (impairing speaking) or to Wernicke’s
area (impairing understanding).
Broca’s Area
= controls language expression that directs
the muscle movements involved in
speech.
Wernicke’s Area
= controls language reception – a brain area
involved in language comprehension and
expression; usually in the left temporal
lobe.
Plasticity
= the brain’s ability to change, especially
during childhood, by reorganizing after
damage or by building new pathways
based on experience.
Neurogenesis
= the formation of new neurons.
Corpus Callosum
= the large band of neural fibers connecting
the two brain hemispheres and carrying
messages between them.
Split Brain
= a condition resulting from surgery that
isolates the brain’s two hemispheres by
cutting the fibers (mainly those of the
corpus callosum) connecting them.
Consciousness
= our awareness of ourselves and our
environment.
Cognitive Neuroscience
= the interdisciplinary study of the brain
activity linked with cognition (including
perception, thinking, memory and
language).
Dual Processing
=the principle that information is often
simultaneously processed on separate
conscious and unconscious tracks.